Jack Crusher's recorded holomessage to Wesley sees him wearing the TWOK uniform. Presumably this was recorded around the time Wes was born, or about to be born. Picard's crew aboard the Stargazer wear the TNG uniforms. I assume the change must have happened somewhere between Wes's birth and the Stargazer's destruction. How old was Wesley at the start of TNG?

Wesley was born in 2348, so he would have been about sixteen at the start of the series.

--Sran

__________________"He clapped his captain—his friend—on the shoulder. Yes, this man was very much like James Kirk, in all the ways that mattered." --Christopher L. Bennett-- Star Trek: Mere Anarachy, The Darkness Drops Again